The rising popularity of wireless communication and the potential of a spectrum shortage have motivated the United States Federal Communications Commission (FCC) to take steps towards releasing multiple bands of spectrum for dynamic spectrum sharing. The government's interest in re-purposing the spectrum for sharing is motivated by the fact that the actual utilization of the spectrum is sparse in practice. For instance, FIG. 1A from the Microsoft Spectrum Observatory in Seattle, Wash., USA (i.e., an example of an urban area), shows that large swaths of spectrum in the gigahertz (GHz) range remain underutilized in this region. To use the spectrum more efficiently, the President's Council of Advisors on Science and Technology (PCAST) has advocated dynamic sharing of much of the currently under-utilized spectrum, which would create GHz-wide spectrum superhighways that can be shared by many different types of wireless services (just as vehicles share a superhighway by moving from one lane to another). For example, multiple ultra-wideband links can share the same wideband spectrum by using orthogonal time-hopping codes for time-modulated systems, or orthogonal pulses and orthogonal codes for fast-pulse-based systems.
Existing methods for spectrum sensing, like those used in the Microsoft Spectrum Observatory, rely on sequential hopping from one relatively small portion of the spectrum (e.g., a “channel” or “band”) to another relatively small portion of the spectrum, typically acquiring only tens of MHz at a time. In another example of spectrum sensing, some conventional spectrum analyzers (e.g., the SPECMON series spectrum analyzers from Tektronix, see hwww.tek.com/spectrum-analyzer/specmon) offer advertised real time bandwidths of up to 165 MHz. In either of the foregoing examples, however, respective and relatively smaller bands of a wider overall spectrum are monitored only occasionally, making it easy to miss short lived signals (e.g., radar) in a given band of a wider swath of GHz spectrum.